Self-accommodation in Ti–Nb shape memory alloys

Chai, Yaw Wang; Kim, Hee-Young; Hosoda, Hideki; Miyazaki, S.

doi:10.1016/j.actamat.2009.04.051

Cited by 165 publications

(76 citation statements)

References 37 publications

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“…It has been reported that the junction planes of these variants are {111} type I twin [13]. The T-cluster observed in the present study is the type identical to the T-clusters observed in cubicorthorhombic transformation in previous studies in other alloy systems [12,18]. The formation process of the T-cluster is shown in detail.…”

Section: -P2supporting

confidence: 67%

Formation Process of Triangular Morphology of Self-Accommodation Martensite in Ti-Nb-Al Shape Memory Alloy

Kamioka

Tahara

Hosoda

et al. 2015

MATEC Web of Conferences

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Abstract. The formation process of a habit plane variant (HPV) cluster with triangular morphology (T-cluster) in TiNb-Al shape memory alloy was investigated by in-situ optical microscopy. Upon cooling the specimen, martensitic transformation occurred and two types of V-shaped clusters and the T-clusters were observed. Two types of V-shaped cluster were the cluster connected by the {111} type I twin (VI) and the cluster connected by the <211> type II twin (VII). The T-cluster is formed by the connection of three HPVs by {111} type I twin. The T-cluster is formed by the growth of the third HPV that is nucleated at the tip of a HPV in a VI-cluster and exhibits inward growth. It is suggested that the T-cluster is a derivative of the VI-cluster. This growth behaviour is discussed based on the incompatibility of the clusters.

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Section: -P2supporting

confidence: 67%

Formation Process of Triangular Morphology of Self-Accommodation Martensite in Ti-Nb-Al Shape Memory Alloy

Kamioka

Tahara

Hosoda

et al. 2015

MATEC Web of Conferences

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“…4,5) Pure titanium is not suitable for all purposes due to high melting point, high reactivity with oxygen and absence of shape memory and superelastic properties, many titanium alloys have been developed for biomedical and engineering applications and their properties have been evaluated mainly to improve the biocompatibility and biofunctionality as implant material. [6][7][8][9][10][11] Advantages of titanium alloys over or ( þ ) alloys are their lower modulus and better formability. 7) The relatively low modulus of titanium alloys that can reduce the ''stress-shielding'' effect 8,9) has also drawn much attention to researchers.…”

Section: Introductionmentioning

confidence: 99%

“…For biomedical applications, recently a systematic investigation has been carried out by our group for Ti-Nb and Ti-Mo alloys. [10][11][12][13][14][15] type Ti-based alloys exhibit phase (disordered bcc) at higher temperatures and phase (hcp, c=a ¼ 1:587) at lower temperatures. type titanium alloys also exhibit three metastable phases, 0 (hcp),…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Ti-<I>x</I>Cr-3Sn Alloys for Biomedical Applications

et al. 2011

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In order to replace toxic nickel element from NiTi biomaterials, Ti-Cr and Ti-Cr-X alloys are also new nickel free titanium based alloys for biomedical applications. In this study, comparative study of Ti-xCr-3Sn (x ¼ 4, 5, 6, 7, 8 and 9 mol%) alloys was carried out. Ti-4Cr-3Sn and Ti5Cr-3Sn alloys were composed of 0 martensitic phase (hcp) and other alloys with 6, 7, 8 and 9 mol% Cr were single phase at room temperature. Among the developed alloys, Ti-6Cr-3Sn alloy showed maximum fracture strain, maximum shape memory effect, maximum pseudoelastic response and minimum hardness and minimum yield stress due to transformation of metastable phase to stress induced martensite during mechanical loading. Vickers hardness and UTS has increased and fracture strain has decreased with greater than 6 mol% addition of chromium in Ti-xCr-3Sn alloys due to solid solution strengthening, phase stabilization and slip as dominant deformation mechanism. It is concluded that among the developed Ti-xCr-3Sn alloys, Ti-6Cr-3Sn alloy is hopeful new alloy for biomedical applications.

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“…Among the potential compositions, Ti-Nb based alloys are the most common biomedical candidate materials because of the combination of good biocompatibility and mechanical properties as detailed in the last section [93,112]. Depending on the Nb content, binary Ti-Nb alloys can display a fully α″ martensitic microstructure at room temperature and thus exhibit shape memory properties [12,113].…”

Section: 2mentioning

confidence: 99%

“…2.3 [134]. By application of the Burger orientation relationship, each β grain is decomposed into several possible α″ variants by application of six possible lattice correspondences, leading to a α″ self-accommodating microstructure at room-temperature and potential superelasticity [135,136]. [23,134].…”

Section: Identification Of α″ Phasementioning

confidence: 99%

Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

Yao-wu¹

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Fine tube stents are used for maintaining localised flow in stenotic blood vessels. Elasticity and plasticity for expansion, rigidity for resisting bending under force and strength to prevent unexpected failure, are required properties of the tubes from which these stents are formed. Biomedical metastable β titanium alloys have been developed as implant materials for a large number of biomedical applications due to a combination of favourable characteristics, e.g. good biocompatibility, excellent toughness and corrosion resistance. A metastable β alloy, Ti-25Nb-3Mo-3Zr-2Sn, has been developed without toxic alloying elements, which is a promising candidate material for stent applications. Metallic materials used for stents are commonly not biodegradable and implanted in the vessel permanently, which may provoke in-stent restenosis and stent thrombosis. In order to remove the implanted materials after service, biodegradable materials, absorbed by the body slowly, are also a field of research interest. Magnesium alloys have been used in studies for biomedical stent applications as a new biodegradable material. Magnesium stents can reopen the blocked blood vessels temporarily before degrading in physiological environments. In addition to the biodegradable characteristics, their mechanical properties are reasonable. The Mg-3Al-1Zn (AZ31) alloy is the subject of some research on the processing of biomedical magnesium alloys as it is a commonly available commercial alloy. Consequently, the Ti-25Nb-3Mo-3Zr-2Sn alloy and the AZ31 magnesium alloy have been used in this thesis to investigate the evolution of mechanical properties and microstructure in the processing of fine tubes.The deformation mechanisms during cold deformation of metastable β titanium alloys are mainly associated with martensitic phase transformations and mechanical twinning. It has been reported that stress-induced phase transformations and {112}〈111〉, {332}〈113〉 twinning modes may be activated under different stress states in metastable β titanium alloys. They can exhibit varying elasticity, Young's modulus and strain hardening behaviour. Because the martensitic start temperature is below room temperature for most metastable β titanium alloys, the α″ martensitic transformation can easily occur under a small amount of external stress. Mechanical twins were reported to hinder slip and dislocation motion thereby increasing the strain hardening rate. The development of β and α″ texture during processing is another critical influence on the mechanical properties of fine tubes. Therefore, studies on the martensitic transformation, mechanical twins and texture evolution is of significance in order to understand the processing of β titanium fine tubes.ii Magnesium alloys deform through the formation of a large amount of mechanical twins due to the relatively low critical stress to activate twinning in comparison with 〈 + 〉 slip. There are typically two primary mechanical twinning modes for magnesium alloys, {101 ̅ 2} extension twins and {101 ̅ 1} cont...

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Self-accommodation in Ti–Nb shape memory alloys

Cited by 165 publications

References 37 publications

Formation Process of Triangular Morphology of Self-Accommodation Martensite in Ti-Nb-Al Shape Memory Alloy

Formation Process of Triangular Morphology of Self-Accommodation Martensite in Ti-Nb-Al Shape Memory Alloy

Comparative Study of Ti-<I>x</I>Cr-3Sn Alloys for Biomedical Applications

Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

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